1. Field
The invention relates to modular construction systems that have releasable snap-fit connection elements that are actually interlocking features of the construction elements themselves, which can be integrated into many differently shaped construction elements and be useful in a variety of fields.
2. Prior Art
Construction systems incorporating various methods of connecting construction elements together are known in the art. Many construction elements connect primarily on one or two faces. One construction toy that connects on two faces is the brand xe2x80x9cLego Classic,xe2x80x9d shown in U.S. Pat. No. 3,005,282. A stud and friction-fit type of connection is used on what are generally considered to be the top and bottom faces of a construction block. This type of connection system is deficient however, as these blocks may not be connected on the other faces, such as side-to-side in a single layer in order to create a span, or overhang, or to construct a beam projecting outwards. Such blocks can be inexpensively produced with simple plastic injection molds. The same studs could be added to more faces, however this would result in more expensive production.
Construction elements with connection elements on more than two faces have been developed. The most common form seen in toys is of the brand xe2x80x9cLego Technic,xe2x80x9d which uses studs and cavities on the top and bottom faces, and through-holes projecting through two of the remaining faces of block and beam construction elements. Snap-fit pins pushed through the holes can be used to connect two or more construction elements together. Such construction elements require more expensive molds to produce than the xe2x80x9cLego Classicxe2x80x9d type because the draw in the mold is in more than one direction. Using holes rather than extra studs and cavities results in more flexibility in construction. Engaging many construction elements together side-to-side with snap-fit pins is not considered very practical however.
Another method of engaging construction elements together that is less common in toys but more popular in larger construction systems is the dovetail connection. For example, U.S. Pat. No. 2,619,829 by xe2x80x9cTatumxe2x80x9d shows a hollow construction block, suitable for blocks made of concrete, which contains one fixed male, and one or more female dovetails in the side of the block. A separate double male connecter is also provided to connect two opposing female dovetails when required. Such a system can connect blocks together on all sides. As well, both the male as well as female dovetails extend only halfway down the block""s sides. This results in a bottom ledge in the female dovetail and prevents the captive male dovetail from sliding through. Of course there is nothing to prevent the male dovetail from sliding back out again. The block faces having dovetails can be secured in only five of six spatial directions. When such blocks are used in multi-layer constructions such as walls, most of the half-height male and female dovetails become captive between adjacent blocks. This reduces the problem of connections coming apart somewhat. There is a problem however in using this system to construct single layer longitudinal objects such as floors or beams.
A similar half-height dovetail connection method is used on toy blocks of the brand name xe2x80x9cKitslink,xe2x80x9d which is shown in U.S. Pat. No. 6,050,044. In this system however, a stud and cavity friction-fit type of connection is used to connect blocks on the top and bottom faces as well. This design allows construction elements to be engaged to each other on all six faces, but still the dovetail sides can be secured in only five of six spatial directions. This is more of a problem with toys where more complex structures are constructed as opposed to constructing walls in the previously mentioned construction system. One way of keeping the dovetails from sliding apart would be to use a friction fit, but this would make the blocks quite hard to put together and especially to take apart. A real disadvantage of this system when used for toys is that the blocks cannot be pushed together in the longitudinal direction of the faces that contain the dovetails. Instead, the block with the male dovetail must be lowered vertically into the female dovetail. As well, when dismantling the structures, the dovetails must be withdrawn in the opposite direction of the assembly. The right direction of disassembly is not clear when viewing the built structures. When single layer, long beamlike objects are assembled, the half-height dovetails can be subjected to tremendous stress if they are handled roughly during play. It is not very difficult to tear apart the dovetails, in which case the blocks become permanently damaged.
Yet another toy block with brand name xe2x80x9cMorphunxe2x80x9d is shown in U.S. Pat. No. 5,957,744. This block uses full-length female dovetail or star shaped grooves in the block sides. To connect the blocks together, they are placed side-by-side and a star shaped connecter is inserted into the facing grooves. This design also does not require studs or other connecting means on the top and bottom faces because the star shaped connecters can be taller than the blocks and so can join blocks both vertically as well as longitudinally. The star shaped connecter is slightly flexible and is designed to have a reasonable friction-fit or a mild compression lock. This makes the structures much more secure than with the previous dovetail design, and blocks can be secured on six faces in six spatial directions. However the blocks still cannot be pushed together longitudinally on the dovetailed sides and must be carefully slid apart from the star shaped connecters to avoid being damaged. The star shaped connecters are generally small and so could cause choking in children if they are swallowed.
While both the xe2x80x9cKitslinkxe2x80x9d and xe2x80x9cMorphunxe2x80x9d designs result in much more elaborate constructions than can be created using the standard xe2x80x9cLego Classicxe2x80x9d construction blocks that locate on only two faces, both have two inherent problems. Construction using these blocks must be done in layers, as the blocks cannot be engaged longitudinally or inserted in the middle of structures. As well, the blocks are meant to be disassembled by carefully sliding apart the blocks or connection elements, and rough disassembly can result in severe damage to the connection elements on the blocks.
The solution to the problem of careful assembly and disassembly has often been to use a type of snap-fit connection. In U.S. Pat. No. 2,885,822 by xe2x80x9cOnanian,xe2x80x9d a block and beam construction system using split hollow blocks with holes in every face is shown. A round double male snap-fit connection element with a pair of outward facing ribs is used to connect blocks together. Such structures can be snap-fit together or apart and can be secured on six faces in six spatial directions. While this design solves the problems of damage to blocks through rough disassembly, the blocks can only be inserted directly towards the face. This design is therefore deficient in that it does not allow for blocks to slid into a space. As well, the production of hollow two part blocks is expensive and the small separate male connection elements are difficult to remove and could also be a choking hazard for children.
A popular snap-fit strut type of construction system with brand name xe2x80x9cK""nexxe2x80x9d is show in U.S. Pat. No. 5,061,219. In this case, male rods are snap-fit sideways into female fittings, but now engaging or separating along the length of the rods is not possible. It is true that the connections don""t need to be carefully slid apart, but separation by a bending action can result in high point contact loads that may result in some damage to parts. A somewhat similar rod type construction system is also shown in U.S. Pat. No. 5,704,186 by xe2x80x9cAlcalayxe2x80x9d.
Another design shown in U.S. Pat. No. 5,518,434 by xe2x80x9cZieglerxe2x80x9d shows a toy construction system using beams having a pair of rounded flexible male fingers which snap-fit into a female square recess. Beams are snap-fit together end to end but not side to side. The rounded snap-fit fingers allow twisting the connection. This could be an advantage or a disadvantage depending on the models being built.
A more versatile snap-fit design with brand name xe2x80x9cLego Znapxe2x80x9d is shown in U.S. Pat. No. 5,984,756. In this beam construction system, a pair of flexible female fingers snap-fit onto a squared male plug. Connections can be separated sideways or longitudinally with no damage to the parts.
Various other snap-fit construction elements have been suggested as well. For example, U.S. Pat. No. 4,126,978 by xe2x80x9cHellerxe2x80x9d shows an extruded construction channel using a pair of male ribs which snap-fit into a female recess with grooves. U.S. Pat. No. 3,815,311 by xe2x80x9cNisulaxe2x80x9d shows another extruded construction module which contains male ribs which snap-fit into separate female recesses. A construction block, shown in U.S. Pat. No. 5,970,673 by xe2x80x9cFisherxe2x80x9d shows paired male fingers which snap-fit into female slots. Another toy, shown in U.S. Pat. No. 4,253,268 by xe2x80x9cMayrxe2x80x9d shows a pair of male curved ribs which slide around an open ended female recess containing a central post.
Snap-fit connections, especially for toys, are desirable because they can result in secure side connections, they prevent damage to parts on disassembly, and they are fast to assemble and disassemble. The disadvantage of open sided snap-fit systems such as the extruded channels by xe2x80x9cHellerxe2x80x9d is that there is no provision for preventing the joined elements from sliding in the direction of the grooves. They are meant for construction systems where a natural ledge such as a floor prevents movement. Designs such as xe2x80x9cZnap,xe2x80x9d xe2x80x9cZiegler,xe2x80x9d and xe2x80x9cK""nex,xe2x80x9d use projections at the ends of the two open sides of the female recess. On xe2x80x9cZnapxe2x80x9d and xe2x80x9cZieglerxe2x80x9d designs, only one ledge is used per female recess side. This still locks the connection together in six of six possible spatial directions but is much easier to mold than if paired ledges were used on each female recess side. The disadvantage of such ledges on the ends of the female open sides is that it is difficult to assemble construction elements because the flexible snap-fit members must be bent rapidly at the very start of the connection as there is not enough distance available generally for a gradual compression.
The invention is a new modular construction system that incorporates a novel snap-fit type of connection system that overcomes many of the previously mentioned problems of construction systems. The objects and advantages of the invention are:
(a) that construction elements can be easily molded with simple molds which have a draw in a single direction or by other inexpensive production methods. No system has been suggested previously that has so many advantages and features as the invention and yet can be so easily produced.
(b) to provide a connection system that is suitable to be used both for construction blocks as well as a wide variety of other construction elements. No system has been suggested previously that can be built in so many different configurations as the invention.
(c) to provide a connection system that allows construction elements to be engaged or separated by either pushing toward each other or apart, or sliding together or apart. It appears that only the prior art xe2x80x9cZnapxe2x80x9d system can be assembled and disassembled in so many directions, but this system is not practical for block construction elements, and is harder to assemble than the invention.
(d) to provide a snap-fit connection element that can secure construction elements in six of six possible spatial directions. Several prior art systems mentioned can do this, however they can not be used in as many configurations or have the same ease of use as the invention.
(e) to provide a construction element that is not required to be made of multiple pieces. Some prior art such as xe2x80x9cTatumxe2x80x9d use hollow blocks made of two pieces to achieve some of the advantages claimed in the invention.
(f) to provide a construction system where the connection elements can be molded integral with the construction element. Some prior art toy systems such as xe2x80x9cMorphunxe2x80x9d require separate connection elements to be used for engaging construction elements together to achieve the claimed advantages over prior art, but this could be a choking hazard for children. Most embodiments of the invention do not require separate connection element pieces to be used.
(g) to provide a construction system where the connection elements have little play when construction elements are put together yet allows the construction elements to be put together and taken apart with little effort. Other prior art such as xe2x80x9cKitslinkxe2x80x9d with its rigid dovetail connection system requires a small amount of clearance between parts for easy assembly. In the invention, the flexible snap-fit elements remove this play.
(h) to provide a connection system where both integral and separate connection elements can be used. Very few prior art designs can use both. The invention allows more complex construction systems to be made by being able to use both systems.
(i) to provide a construction system where extremely close manufacturing tolerances are not required. Some other snap-fit construction elements with nearly right-angle connection contact angles require extremely tight manufacturing tolerances. In the invention, less than right-angle connection contact angles are preferably used where the connection play can be removed entirely even with normal manufacturing tolerances.
(j) to provide a construction system where two construction elements can be slid together easily during the beginning of the connecting process, which requires less dexterity in construction. In other designs such as xe2x80x9cK""nexxe2x80x9d and xe2x80x9cZnap,xe2x80x9d it is often hard to feel where the connection elements will go together. For example, in the xe2x80x9cZnapxe2x80x9d design, when inserting the male connection element into the female connection element vertically, the flexible walls must be bent apart quickly at the very start of the connection. In the invention, with this type of sliding together of connection elements, the male ribs can be inserted almost half way down the female recess till encountering some projections. This makes it much easier to start assembling the two construction elements before applying more pressure to ride over these projections.
(k) to provide a connection system where it is hard to damage the connection elements during rough engagement or separation. In other designs such as xe2x80x9cKitslink,xe2x80x9d the dovetail connection elements can be easily damaged. In the invention, the snap-fit connection method reduces the possible damage substantially by being designed to separate in many different directions.
(l) to provide a construction system that can be used with other popular construction systems. The various different configurations of the invention can be built to allow mating with a larger variety of other construction systems, and allow more adaptors to be built.
(m) to provide a construction system that can be made of inexpensive materials. Some prior art snap-fit systems such as xe2x80x9cK""nexxe2x80x9d and xe2x80x9cZnapxe2x80x9d are largely made of expensive Acetal plastic resin. The invention allows cheaper plastics such as Polypropylene to be used in many of the configurations.
(n) to make the construction elements look good. Some other prior art such as xe2x80x9cZnapxe2x80x9d do not fit together with the same clean lines due to the design of the snap-fit connection elements. Most embodiments of the invention result in two interlocking connection elements where only a simple rectangular space remains. As well, parts of the connection elements can be molded flush with the top and bottom surfaces of the construction element giving a clean, flush appearance. The full height connection element features of the invention especially look good when many block construction elements are stacked vertically. The continuous male ribs and female anti-twist bars on such walls and columns give them a rich Gothic ribbed appearance.
(o) that construction elements can be engaged on all sides. Some prior art such as xe2x80x9cLego Technicxe2x80x9d cannot be engaged together on all sides even though this design requires more expensive molds. In the invention all sides can be engaged while still being able to be produced with inexpensive molds.
(p) that construction element can be non-handed. In some prior art such as xe2x80x9cKitslinkxe2x80x9d there is either a male or a female dovetail connection element on sides using dovetail connection elements. This requires turning each block to the proper orientation when assembling. In the preferred embodiment of the invention, a male and a female connection element are paired, which makes the connection non-handed.
(q) that construction elements can be engaged inverted. In some prior art such as xe2x80x9cKitslinkxe2x80x9d or xe2x80x9cTatum,xe2x80x9d upright construction elements cannot generally be engaged to inverted ones. They can be if in a vertically staggered position only. In the invention, many types of upright construction elements can be engaged to inverted ones, though in the preferred embodiment the blocks must be staggered horizontally to do so.
(r) that construction elements can be engaged staggered vertically. In some prior art designs such as xe2x80x9cOnanian,xe2x80x9d each face of the construction elements must match. In the invention, construction elements can be securely engaged half-way vertically between two other construction elements.
(s) that the connection elements fit between the confines of a stud and cavity construction system. In some prior art such as xe2x80x9cKitslink,xe2x80x9d the dovetail connection elements protrude too far beyond the side surfaces of the construction element and so must be placed between a pair of studs on construction blocks. In the invention, the connection elements are located partly inside and partly on the outside of the side surfaces, which allows the connection elements to be placed directly between two studs.
(t) that the connection protrudes minimally outside the construction element. Again, on prior art such as xe2x80x9cKitslink,xe2x80x9d the connection elements protrude substantially beyond the sides of the construction elements. In the invention, the connection element is located partly inside and partly on the outside of the side surfaces, which reduces the distance the connection elements project to the outside of the construction element.
(u) to provide a construction system where a construction element will sit level when placed on its side. On some prior art designs such as xe2x80x9cKitslink,xe2x80x9d a single male dovetail projecting beyond the sides of the construction element does not allow the blocks to stand level by themselves. In the preferred embodiment of the invention, paired connection elements are used. Anti-twist bars, which are extensions of the female connection element, project outward the same distance as the male ribs, and this allows single blocks to be placed level on the sides containing the snap-fit connection elements. The connection elements also preferably extend the full height of each face, which results in even more stability when they are stood on their sides.
(v) allows use of an extra connection locking device. Some prior art such as xe2x80x9cTatumxe2x80x9d and xe2x80x9cKitslinkxe2x80x9d use dovetail connection elements that result in a very rigid connection that doesn""t come apart as readily as a snap-fit connection in general. But these systems are prone to damage through rough handling. In the invention, especially when used in larger construction systems, a wedge spacer can be inserted in the space between the male ribs, which prevents the connection element from separating in all six spatial directions. The ridges and projections holding together the connection however are much less in height than the typical dovetail, which still reduces the chances of damage to the connection over the dovetail connections mentioned when connection elements are forced apart.
A modular construction system featuring an improved snap-fit connection system that can be incorporated into a wide variety of modular type construction elements. In the invention, all connection elements are of two categories. First they may be either male or female, where the male is a rib-like member than enters a female recess. Secondly the two mating connection elements can also be of either type one or type two. In all embodiments of the invention, the definition of a type one connection is that it contains ridges and indentations and is the more resiliently bendable connection element, while the definition of a type two connection is that it contains grooves and projections and is the less resiliently bendable connection element.
In the preferred embodiment of the invention, the type one connection is male and consists of a pair of flexible ribs containing ridges and indentations. These ribs snap-fit into the recess of the type two connection element which is female, consisting of rigid opposed walls which contain grooves and projections. When the connection elements are engaged, the paired ribs fit tightly between the opposed walls which prevents movement in the horizontal direction. The ridges on the ribs locate into the grooves of the opposed walls which prevents movement in the longitudinal direction. The indentations in the ridges locate over the projections in the grooves and this prevent movement in the vertical direction. The female connection element is open on the top, bottom, and front faces. In the preferred embodiment, this allows the connection element to be either slid together vertically from the top or bottom, or longitudinally from the front, or the connection elements can be rolled together. The connection elements can also be separated by the reverse procedure.
The connection element of the invention is superior to the prior art, as centrally located indentations and projections are used to prevent the connection from sliding apart. Other connection systems in this general snap-fit class use projections on the open sides of a female connection element, which are more difficult to assemble. Other novel aspects of the invention allow for a much larger variety of construction elements than the prior art. Many snap-fit type connection elements are considered to be hard to mold, but this connection element both can be engaged or separated easily in a variety of directions while still being able to be molded inexpensively.